3 Stars
I have now completed all 90 levels available with approx 2/3 getting 3 stars. There are 32 levels that I have only achieved 1 or 2 stars and of the majority of those 32 I think it will be impossible to reach 3 stars as there are not enough birds and or points generating items per sub level or there are only one or 2 sub levels.
I will replay them all and see how I go.
Anyone else noticed?